1. Technical Field
The present invention relates to a semiconductor integrated circuit, and more particularly, to an EMI shielding circuit.
2. Related Art
As semiconductor integrated circuits are highly integrated and operated at a high speed, electromagnetic waves are generated by the electrical signals propagating inside the semiconductor integrated circuits. Interference due to these electromagnetic waves, or electromagnetic interference (EMI), may affect operation of the semiconductor integrated circuits and other circuits.
Furthermore, as semiconductor memory devices are highly integrated and operated at a high speed, EMI is induced in the semiconductor memory devices and external circuits due to electromagnetic waves generated by electric signals of the semiconductor memory devices in data input/output operations of the semiconductor memory devices. Therefore, a semiconductor memory device for storing data and outputting the stored data and a semiconductor integrated circuit including the same should include an EMI shielding circuit.
The EMI shielding circuit uses methods including spread spectrum clocking (SSC), differential signaling, etc. However, the effective timing period of a signal is decreased when using the SSC, and the area of a circuit is increased in the differential signaling.